Welding electrode cap

ABSTRACT

A domed copper electrode tip has a refractory insert inserted thereinto extending from the apogee of the dome into the interior of the electrode. The refractory insert is, preferably, a tungsten insert which is force-fitted into the interior of the electrode tip.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of Application, Ser. No.15/568,012, filed Oct. 20, 2017 for “IMPROVED WELDING ELECTRODE CAP”,the disclosure which is hereby incorporated by reference, including thedrawing.

BACKGROUND OF THE INVENTION 1. Field of Invention

This invention relates, in general, to resistance spot welding equipmentand, more specifically, to resistance spot welding electrodes. Moreparticularly, the present invention concerns replaceable resistance spotwelding electrode caps. Even more particularly, the present inventionconcerns means and methods for improving the thermal heat dissipationproperties of such welding electrode caps.

2. Description of Related Art

In the above referred to co-pending application there is disclosed animproved electrode tip which provides greater cooling surface for theinterior fins thereof by having chamfered ends.

The chamfered ends are intended to provide greater surface area for theliquid coolant which is introduced into the interior in association withsuch finned electrodes.

However, one of the deficiencies which is continuously encountered withsuch electrode tips is their useful life. Because of the heat generatedduring the robotic welding process the life of these tips, even in spiteof the coolant being introduced into the interior thereof, still is notsatisfactory.

Thus, there exists a need in the art for improving the useful life ofthese electrode tips. It is to this to which the present invention isdirected.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided an electrodetip having an improved useful life and which, generally, comprises: adomed copper-based electrode tip having a refractory material insertdisposed centrally and medially of the tip at the apogee thereof.

Since the refractory material has a melting point far in excess of thatof the electrode tip the insert serves to increase the useful lifethereof. The refractory insert is installed at the apogee of the dome byforce-fitting thereinto.

In order to effectuate the insert a small opening is formed at the tipof the dome. Thereafter, the refracting material is forced therethroughuntil it is disposed fully in the interior of the electrode tip with itsouter surface being co-planar and circumferentially integrated into theexterior of the tip.

For a more complete understanding of the present invention reference ismade to the following detailed description and accompany drawing.

In the drawing like reference characters refer to like parts throughoutthe several views, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C illustrate, in cross-section, the insertion of a refractoryinsert into a standard electrode tip in accordance with the presentinvention; and

FIG. 2A-2C illustrate, in cross-section, the insertion of a refractoryinsert into a finned electrode.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Now, and with reference to the drawing and, in particular, FIG. 1, thereis depicted therein an electrode tip 10. The tip 10 is of the typecomprising a substantially cylindrical sidewall 12 with a dome tip 14integrally formed therewith. The tip has a hollow interior 15 having anentry 16 for receiving an electrode shank 19.

As is known to the skilled artisan a robotic electrode tip 10 istypically formed from copper or a dispersion strengthened copper alloy.Such materials are well known to the skilled artisan.

Further, as is known to the skilled artisan such copper or copper-basedelectrode tips have a melting point of about 1100° F. Under ordinaryconditions robotic welding will typically take place at the meltingtemperature of steel, i.e. about 2750° F. Because of high temperaturesat which welding occurs such electrode tips, generally, have a usefullife of about 2500 to about 3600 welds.

In accordance herewith and as shown in the drawing a medial or centralrefractory insert 20 is inserted into the interior 15 of the tip and hasa length extending from the apogee 21 of the tip of the electrode shankto the interior terminus 22 of the dome 14 of the tip 10 and is impartedwith a curvature or other shape such that it is contiguous with the domeof the tip such that there are no discontinuities associated therewith.

The refractory material may be of any type which has a melting point inexcess of that of the copper or copper alloy.

Preferably, among the useful refractory materials are, for example,molybdenum, rhenium, niobium, tungsten, tantalum and the like. Thepreferred refractory material is tungsten which has a melting point ofapproximately 6200° F.

The tungsten insert can be manufactured by any suitable well knownmethod including powder metallurgical processing.

Referring again to the drawing, the refractory insert 20 is insertedinto the tip 14 by initially providing a small opening 24 in the dome byany suitable means such as by a punch or the like as well as by drillingin a secondary operation. The insert is, then, force-fitted into theinterior of the tip until it reaches with the interior terminus of theelectrode top.

Any discontinuities are avoided through the force-fitting by having thetungsten insert by being of a diameter slightly larger than that of thepierced or drilled opening into which it is inserted.

The insert can be force-fitted through any suitable means includingmanually with a hammer or through any automatic press or the like.

It is to be appreciated herein that the present invention is applicableto any type of copper-based electrode tip be it internally finned suchas shown in FIGS. 2A-2C or the standard, non-finned electrode of FIGS.1A-1C.

Having thus described the invention, what is claimed is:

INDEX OF REFERENCE NUMERALS

Electrode tip 10

Sidewall 12

Dome 14

Interior 15

Entry 16

Electrode

-   -   Shank 19

Insert 20

Apogee 21

Dome Interior

-   -   Terminus 22

Opening 24

1. In a copper-based electrode tip of the type having a domed top, theimprovement which comprises: a refractory material insert extending fromthe apogee of the dome into the interior of the electrode tip.
 2. Theimprovement of claim 1 wherein the refractory material is selected fromthe group consisting of molybdenum, rhenium, niobium, tantalum andtungsten
 3. The improvement of claim 2 wherein the refractory materialis tungsten.
 4. The improvement of claim 1 wherein the electrode tip isan interiorly finned electrode.
 5. The improvement of claim 1 whereinthe electrode tip is a copper tip.
 6. The improvement of claim 1 whereinthe electrode tip is a dispersion strengthened copper tip.
 7. A methodfor manufacturing an electrode tip comprising: piercing an opening intothe electrode tip and force-fitting a refractory insert from theexterior surface of the tip of the electrode into the interior thereof.